My #5 heads are at the shop for a 2.000/1.625 upgrade...which sounded simple enough ! ("Just drop in BBO valves..W-31 style!")

BUT...my original 1.875/1.562 valves are around 4.735" OAL (stock lists @ 4.740).
The only 2.000/1.625 valves I've found are in the 4.660-4.695 OAL range.

That's a difference of .035-.080.

Anyone have a source for 4.740 length BBO valves ?
Or, how do I get around this ?

The machinist says he can source something with an OAL closer to 4.74, but with heads bigger than 2.000/1.625, and cut them down to 2.000/1.625.

OR, it looks like I'm headed for an adjustable valvetrain upgrade that I hadn't planed on...

I know there's a bunch of you running these size valves in SBOs..

What say CO ???

TIA

 

Paladin Mechanics

1421 Sw 1st Way
Deerfield Beach, FL 33441-6753
(954) 428-8795 Try these guys, they did the heads on my W31, my reciept does not give any part #'s.

 

The length of the valve is not important - it's the installed height of the valve tip. How the valve seat is cut will affect the installed height.

 

Thanks, Joe (& 1969w3155 for the response),

I understand the install height is the critical spec due to the non-adjustable rockers. The install height of the old valves was measured for reference. The machinist is concerned about sinking the shorter (BBO length) seats/valves in the head to get the proper install height may push them into unknown territory seat-wise. The shop has done BBOs & SBOs w/standard sizes, but this project has raised questions...

These are #5 heads ( even/shallow spring pockets)....

To me (a newbie when it comes ot head work), a .073 difference (4.740-4.667) seems like a lot....

Has anyone used 4.667/4.695 length BBO valves in a SBO head & getting proper install height without issues?

How did the factory '68-'69 RamRod/W-31s do it ? Did they have longer versions of the BBO valves ? Or did they just sink them to get the install height?

 

Just a bump before I let this sink into history..!

Does anyone know how the '68-'69 RamRod/W-31 BBO valves were done at the factory ?

Did they have 'special' longer versions of the BBO valves ?
Or did they just set the shorter ones deeper in the head ?

 

I don't have that info, though I am curious. My new valves are pretty much dead on in length to yours (2.000 x 4.670 & 4.625 x 4.695) listed on my invoice. When I asked about hardened valve seats, he said "you don't need them as you are going to stainless valves". He said that I could run with my stock pushrod length, but with my cam (Engle 22-25) that they should be changed. (my W is on hold, so I can't provide more info) He is retired from Olds...30 years at valvetrain in Michigan. At the time that I had this done he was campaigning a '70 W31 in L class NHRA.

 

I don't mean to be a jerk but those statements have me wondering.

 

For unleaded gas he said that it was unnecessary as I was going to stainless valves, though I realize the seats are a different matter, but I took his knowledge as correct. As I am not knowledgeable about when to use different length push rods, due to minimal cleanup of the heads, and the lobes of the cam? (but I don't know how much is minimal to true them) He also said not to cut the block. This engine had been rebuilt once before in the early eighties, but what was done as far as machining of the block/heads, is unkown to me. Don't know what his job there was, he just said that in worked in the valvetrain dept for 30 years.